<?php
namespace app\models;
class Helper
{
   public static function truncate_utf8_string($string, $length, $etc = '...')
   {
       $result = '';
       $string = html_entity_decode(trim(strip_tags($string)), ENT_QUOTES, 'UTF-8');
       $strlen = strlen($string);
       for ($i = 0; (($i < $strlen) && ($length > 0)); $i++)
       {
       if ($number = strpos(str_pad(decbin(ord(substr($string, $i, 1))), 8, '0', STR_PAD_LEFT), '0'))
           {
           if ($length < 1.0)
               {
           break;
           }
           $result .= substr($string, $i, $number);
           $length -= 1.0;
           $i += $number - 1;
       }
           else
           {
           $result .= substr($string, $i, 1);
           $length -= 0.5;
       }
       }
       $result = htmlspecialchars($result, ENT_QUOTES, 'UTF-8');
       if ($i < $strlen)
       {
       $result .= $etc;
       }
       return $result;
   }
}
